Question

Помогите решить пожалуйста! Одна бригада рабочих может заасфальтировать 15 км шоссейной дороги за 30 дней, а другая за 60 дней.За сколько дней могут заасфальтировать эту дорогу обе бригады, работая вместе?

Answer 1

30/15=6(км. )
60/15=4(км)
6+4=10(дней)
Ответ : 10 дней

Answer 2

Problem Analysis

We are given that one team of workers can pave 15 km of a highway in 30 days, while another team can pave the same distance in 60 days. We need to determine how many days it will take for both teams to pave the highway if they work together.

Solution

To solve this problem, we can use the concept of work rates. The work rate is defined as the amount of work done per unit of time. In this case, the work rate is measured in kilometers per day.

Let's denote the work rate of the first team as R1 (in km/day) and the work rate of the second team as R2 (in km/day).

From the given information, we know that the first team can pave 15 km in 30 days, so their work rate is:

R1 = 15 km / 30 days = 0.5 km/day.

Similarly, the second team can pave 15 km in 60 days, so their work rate is:

R2 = 15 km / 60 days = 0.25 km/day.

To find the combined work rate of both teams, we can add their individual work rates:

Combined work rate = R1 + R2 = 0.5 km/day + 0.25 km/day = 0.75 km/day.

Now, we can use the combined work rate to determine how many days it will take for both teams to pave the entire highway. Let's denote the number of days required as D.

The total work to be done is 15 km, so we can set up the following equation:

Total work = Combined work rate × Number of days

Substituting the values we have:

15 km = 0.75 km/day × D

Solving for D, we get:

D = 15 km / 0.75 km/day = 20 days.

Therefore, it will take both teams working together 20 days to pave the entire highway.

Answer

Both teams can pave the entire highway by working together in 20 days.

Explanation

The first team has a work rate of 0.5 km/day, which means they can pave 0.5 km of the highway in one day. The second team has a work rate of 0.25 km/day, which means they can pave 0.25 km of the highway in one day. When both teams work together, their combined work rate is 0.75 km/day. This means that they can pave 0.75 km of the highway in one day. Since the total length of the highway is 15 km, it will take both teams 20 days to pave the entire highway.